1. Field of the Disclosure
Embodiments of the disclosure relate to methods and apparatuses for establishing a wireless connection by combining listen and scan windows.
2. Description of the Related Art
Bluetooth® Low Energy (BLE), marketed as Bluetooth® Smart, is a wireless technology for establishing packet-based wireless networks among wireless devices operating in the 2.4 GHz to 2.4835 GHz frequency range with significantly reduced power consumption compared to legacy Bluetooth® devices, sometimes referred to as Classic Bluetooth® devices. Bluetooth® is a registered trademark of the Bluetooth® Special Interest Group (SIG), incorporated in Delaware, with global headquarters in Kirkland, Wash. (See www.bluetooth.org.) The Bluetooth® SIG maintains the specifications for Bluetooth® Smart, presently the Bluetooth® Specification 4.0 and the Bluetooth® Specification 4.1, where version 4.1 provides an update to version 4.0.
Low power wireless devices compliant with the Bluetooth® Smart specification are expected to find applications in healthcare, fitness, security, home appliances, and home entertainment, to name a few examples. Such devices are marketed as Bluetooth® Smart devices, and are expected to run for long periods of time, perhaps years, on a button or coin battery. Bluetooth® Smart Ready devices are wireless devices with dual protocol stacks capable of communicating with legacy Classic Bluetooth® devices as well as Bluetooth® Smart devices. For example, a cellphone may have Bluetooth® Smart Ready capability so that it may communicate with a legacy Classic Bluetooth® headset as well as a personal device having Bluetooth® Smart capability.
A Bluetooth® Smart device may be configured as a central (master) or peripheral (slave). Often the central is a smartphone, tablet, or personal computer. A master may set up a wireless network with multiple peripherals, where connections are established between the master and each peripheral. A Bluetooth® Smart device may also be configured as a server or a client. In practice, the server may be thought of as having data of interest, where a client connects with the server to request the data and perhaps modify the state of the server. Usually, the central is the client and a peripheral is the server.
For example, a Bluetooth® Smart home thermostat may store temperature values over some period of time, and perform as a server and peripheral to a smartphone when the smartphone is brought in proximity to the home thermostat. The home thermostat may advertise itself so that when the smartphone is in range a connection is established with the smartphone as the central and the home thermostat as the peripheral. In this example, the smartphone performs as the client, requesting the stored temperature values from the home thermostat. Based upon an application running on the smartphone, the smartphone may change the state of the thermostat whereby the home thermostat's temperature setting is raised or lowered depending upon the stored temperature readings and other information that the smartphone may access from the home thermostat or perhaps from cloud-based databases.
Bluetooth® Smart technology will find applications in many devices in common use around a home, office, or factory. For example, FIG. 1 illustrates a wireless network in which the smartphone 102 may be a master and client to multiple Bluetooth® Smart capable devices: the wristwatch 104 with a sensor to measure pulse rate; the home thermostat 106; the key fob 108 with stored car seat settings and other car preferences; the athletic shoe 110 with a pedometer; the wrist band 112 with a sensor to measure blood pressure and heart rate; the personal thermometer 114; the weight scale 116; the laptop 118; and the television 120. The smartphone 102 may be connected to the Internet 122 so that various databases may be accessed to store readings or to adjust the state of some of the Bluetooth® Smart devices, or perhaps to alert a health care professional or emergency service personnel if a reading from a Bluetooth® Smart device indicates a health issue or urgent situation.